There is no direct choice between conventional mitigation and climate engineering. We need to accept that the loss of a large percentage of the world's reefs is inevitable, or start thinking beyond conventional mitigation of CO2 emissions. A new solution has been proposed for the forthcoming crisis of the coral reefs in warming tropical oceans: blot out some of the sunlight. Scientists from the US, UK and Australia suggest a form of climate engineering called solar radiation management (SRM), which involves pumping fine particles known as aerosols into the stratosphere reflect incoming sunlight. SRM has already been proposed as a mechanism for cooling the Artic to preserve its sea ice and glaciers, and for wide scale 'whole earth' cooling. But the most pressing purpose for the technology may be to save the world's coral reefs. If sea temperatures rise just 1°C to 2°C above...